IL-1β调控OCT4表达增强ALDH+肿瘤干细胞“干性”的作用机制研究

Our previous study demonstrated that the cancer stem cell vaccine could selectively target CSC (cancer stem cell), which resulted in decreased expression of IL-1β; recombinant IL-1β could up-regulate the percentage of ALDH+CSC, promote the sphere formation ability and up-regulate OCT4 expression. These findings suggested that there was cross-talk between IL-1β and CSC. However, the underlying mechanism was largely unknown. OCT4 was one key gene in maintaining the CSC stemness. Akt-mediated signal pathways was involved in regulating the function of OCT4. Meanwhile it was the downstream signal pathway of IL-1β. Thus, we propose that IL-1β enhances the stemness of CSC by up-regulating the expression of OCT4 through the Akt pathway. This project will study the effect of IL-1β on the stemness of CSC, including the self-renewal, chemo-resistance and tumorigenicity. Then we will evaluate whether IL-1β could up-regulate the expression of OCT4; the RNAi technique would be applied to evaluate the effect of IL-1β on maintaining CSC stemness. After blocking the Akt signal pathway, the effect of IL-1β on the expression of OCT4 will be evaluated, which would provide evidence that IL-1β could up-regulate the expression of OCT4 through Akt pathway. By studying the effect and mechanism of IL-1β-mediated ALDH+CSC stemness, it could provide a novel target to specifically target CSC.

申请人前期发现肿瘤干细胞疫苗可以特异性的靶向肿瘤干细胞（CSC），降低IL-1β表达；IL-1β刺激肿瘤细胞上调ALDH+CSC的百分比，增强球状克隆能力，上调OCT4表达，提示IL-1β与CSC之间有“对话”。然而，IL-1β调控CSC的分子机制尚不清楚。OCT4是干性维持基因，Akt信号通路是调节OCT4的关键通路，亦是IL-1β作用的下游通路。因此，我们假设IL-1β激活Akt通路上调OCT4增强CSC干性作用。本课题拟首先明确IL-1β对CSC干性作用的维持（自我更新、耐药性及成瘤性等）；研究IL-1β对OCT4表达的影响，并检测SiRNA干扰OCT4表达后IL-1β对CSC干性维持的作用；最后利用信号通路抑制剂阻断Akt信号通路，阐明IL-1β激活Akt通路调控OCT4表达的机制。本课题有望揭示IL-1β增强CSC干性的新机制，为靶向CSC提供新的治疗靶点。

肿瘤干细胞是肿瘤复发和转移的根源，目前仍缺乏特异性的靶向肿瘤干细胞的策略。我们前期发现肿瘤干细胞疫苗可以诱导特异性的肿瘤免疫靶向肿瘤干细胞（CSC）,降低IL- 1β表达;IL-1β刺激肿瘤细胞上调ALDH+CSC的百分比,增强球状克隆能力,提示IL-1β、CSC及免疫效应细胞之间有“对话”。然而,IL-1β调控CSC的免疫学机制尚不清楚。我们的研究发现IL-1β能增强并维持肿瘤细胞的干性作用（上调干细胞标记物 ALDH、CD133和CD44；增加无血清培养基中球状克隆形成能力；增强增殖、迁移、侵袭力；有较强的成瘤能力。RNA-seq结果显示在头颈部鳞状细胞癌模型和恶性黑色素瘤模型中IL-1β共同作用的机制表现在能上调肿瘤干细胞分泌 CXCL1和 CXCL10和作用于NF-κB信号通路；进一步的机制研究显示IL-1β通过磷酸化-IκB/NF-κB信号通路，刺激 CXCL1和 CXCL10分泌，募集免疫抑制细胞 Tregs至肿瘤干细胞微环境，从而介导免疫逃逸。该研究为我们下一步通过调控免疫微环境中免疫抑制因子IL-1β联合肿瘤干细胞疫苗治疗肿瘤提供了理论支持。